Fluid press

ABSTRACT

The stamping of a sheet material is accomplished by forcing a liquid against it in such manner that it is formed to the shape of a mold or die element. Use of a liquid produces an even distribution of force against the sheet material and thus reduces breakage while overcoming the need for repetitive stamping in order to obtain complex shapes.

United States Patent De La Sierra 1 June 20, 1972 1 FLUID PRESS [21] Appl.No.: 882,615

[30] Foreign Application Priority Data 3,396,561 8/1968 Day ..72/63 3,180,776 4/1965 I-lessel ..72/63 3,373,585 3/1968 Reynolds ..1 13/120 FOREIGNPA'I'ENTS OR APPLICATIONS 1,121,012 4/1962 Germany ..72/63 Primary Examiner-Richard J. Herbst Attomey-John J. Byme Dec. 5, 1968 Mexico ..l07591 [5 7] ABSTRACT if 5'" B2 The stamping of a sheet material is accomplished by forcing a m f h 72/63 liquid against it in such manner that it is fon'ned to the shape I 1 e o of a mold or die element. Use of a liquid produces an even distribution of force against the sheet material and thus reduces [56] Rdmnm Cited breakage while overcoming the need for repetitive stamping in UNITED STATES PATENTS order to Obtain complex shapes.

2,761,405 9/1956 Miiller ..72/63 1 Claim, 6 Drawing Figures f h /a K 22 FLUID PRESS BACKGROUND OF THE INVENTION 1 Field of the Invention This invention relates to the art of forming or stamping sheet materials and, more particularly, to the art of forming or stamping hot or cold sheet metal by the use of liquid pressure.

2. Description of the Prior Art In conventional mechanical apparatus for stamping or molding sheet material, the molds used vary from the simple, which can be used to form the finished article in one operation, to the complicated, which require two or more stamping operations to form the sheet into the desired shape. The complex molds require great skill on the part of the stamp operator, and even then the slightest deviation from the proper SUMMARY OF THE INVENTION Accordingly, it is an object of this invention to provide apparatus for molding or stamping sheet material, hot or cold, in a single stroke or operation.

It is another object of this invention to provide a new process for stamping or minting in which the dies or molds lack a puncher, and in its place hydraulic pressures are applied to form the sheet material to a desired shape.

It is another object of this invention to provide apparatus for stamping to greater depths than is possible with conventional means.

These and other objects are attained in a stamping arrangement which relies on the application of fluids under pressure to the sheet material which is to be formed or molded. The male part in the stamping apparatus is eliminated, and a noncompressible fluid is pressed against the sheet material, which is deformed in accordance with the configuration of the female part. Since the pressure applied by the fluid is uniform in all directions, the sheet material is deformed gradually, there being no points of extreme stress as there is when a rigid male part is employed. Thus the sheet material is formed along the confines of the female part gradually and in one operation and there is no need for repeated stamping operations to achieve a complex shape. In addition, stamping to greater depths than heretofore possible with rigid male parts is readily accomplished.

BRIEF DESCRIPTION OF THE DRAWING The operation and advantages of stamping apparatus constructed in accordance with this invention will be better understood by reference to the drawing, in which:

FIG. 1 shows stamping apparatus constructed in accordance with the invention at the beginning of the stamping operation;

FIG. 2 shows the apparatus of FIG. 1 during the stamping of a sheet of material;

FIG. 3 shows the conventional method of stamping sheet materials in molds, using male and female parts;

FIG. 4 shows hydraulic stamping of a sheet material in the shape shown in FIG. 3, indicating the distribution of forces during the stamping operation;

FIG. 5 shows stamping of a sheet material into a conical shape by conventional means by deforming the material around the male part;

FIG. 6 shows stamping of the shape shown in FIG. 5 by apparatus constructed in accordance with the invention.

DETAILED DESCRIPTION Apparatus for stamping a sheet of material into a spherical shape of diameter L is shown in cross section FIG. 1; Mold 10 contains a spherical cavity for forming sheet 12, which is held in position against mold 10 by clamp 14 and bolts 15. Cylinder l6'contains fluid 18, which is maintained under pressure by piston 20. The fluid is contained at one end of cylinder 16 by a sheet of elastic material 22. Force F indicates the force used against piston 20 to shape sheet 12.

When force F is applied to piston 20, fluid 18 is displaced from cylinder 16 and sheet 12 is deformed upward, as shown in FIG. 2. The arrows directed against elastic 22 indicates the uniform pressure applied against sheet 12 during deformation. It will be appreciated that as piston 20 is pushed further upward sheet finally comes into contact with the spherical cavity of mold l0 and assumes a spherical shape. With the stamping operation completed, piston 20 is withdrawn downward, and through the action of elastic 22 fluid 18 is returned to cylinder 16. Accordingly, the stamping of sheet 12 into a spherical shape is carried out gradually, in a single stoke operation instead of the multi-stroke operation normally required with conventional apparatus.

In FIG. 3, sheet 30 is shown as it is shaped between male part 32 and female part 34 in customary fashion. It will be apparent that the portion of 30 designated by bracket 36 undergoes extreme tensile stress in this arrangement, and may be easily fractured.

0n the other hand, with apparatus designed in accordance with this invention, as shown schematically in FIG. 4 sheet 30 is shaped gradually by the uniform pressure of fluid 38 until it meets the confines of female part 34, and no single point or region of sheet 30 is subject to extreme stress as in the apparatus shown in FIG. 3.

FIGS. 5 and 6 illustrate the same phenomenon in even clearer terms. In FIG. 5, conical male part 40 is applied against sheet 42 to form a conical shape. It is evident that the flat upper face of male part 40, designated 44, engages sheet 42 initially, and the depth of the shape to be obtained is severely limited by the plasticity and resiliency of sheet 42. If, for example, the depth of the conical shape is increased to the point where the upper face of male part is very small, rupture of sheet 42 may easily occur near the apex of the cone.

This difficulty is overcome by using apparatus such as shown in FIG. 6, wherein fluid 50 is ued to form sheet 52 into the conical shape of female part 54. As the pressure in fluid 50 is increased, sheet 52 is brought into contact first with the widest or open part of part 54, and with further deformation sheet 52 is pressed against the narrower portions of the conical female part 54, as shown by the hatched lines. Accordingly, neither the height nor the conicity of the shape to be obtained is limited as with conventional apparatus.

In a general manner, while there has been disclosed effective and efficient embodiments of the invention, it should be well understood that the invention is not limited to such embodiments as there might be changes made in the arrangement, disposition, and form of the parts without departing from the principle of the present invention.

I claim:

1. Apparatus for stamping sheet material comprising, a female part having a cavity, first clamping means for holding the sheet material to be stamped over said cavity, said first clamping means comprising a first surface of said female part adjacent to and surrounding said cavity and a clamping member having a first side with a second surface thereon opposed to said first surface, said female part and said clamping member being relatively movable toward each other whereby said material to be stamped is engaged by and clamped between said surfaces, a cylinder having an open end underlying said female part, a piston slidably received in said cylinder, an elastomeric sheet extending over said open end and sealing said cylinder, said elastomeric sheet underlying said material to be stamped and having straight free edge portions extending radially outwardly from said cylinder and lying parallel to the plane of said open end, a third surface on said clamping member on a second side thereof opposite said first side, said third surface being vertically aligned with said first and second surfaces, said straight free edge portions lying in engagement and means for moving said piston toward said cavity forcing said fluid against said elastomeric sheet such that said sheet presses said material to be stamped against the internal surfaces of said cavity. 

1. Apparatus for stamping sheet material comprising, a female part having a cavity, first clamping means for holding the sheet material to be stamped over said cavity, said first clamping means comprising a first surface of said female part adjacent to and surrounding said cavity and a clamping member having a first side with a second surface thereon opposed to said first surface, said female part and said clamping member being relaTively movable toward each other whereby said material to be stamped is engaged by and clamped between said surfaces, a cylinder having an open end underlying said female part, a piston slidably received in said cylinder, an elastomeric sheet extending over said open end and sealing said cylinder, said elastomeric sheet underlying said material to be stamped and having straight free edge portions extending radially outwardly from said cylinder and lying parallel to the plane of said open end, a third surface on said clamping member on a second side thereof opposite said first side, said third surface being vertically aligned with said first and second surfaces, said straight free edge portions lying in engagement with said third surface, a second clamping means underlying said free edge portions and said third surface and in vertical alignment therewith, said first and second clamping members being relatively movable toward each other for clamping said elastomeric sheet therebetween, a non-compressible fluid in said cylinder between said piston and said elastomeric sheet, and means for moving said piston toward said cavity forcing said fluid against said elastomeric sheet such that said sheet presses said material to be stamped against the internal surfaces of said cavity. 